The present invention is related to holographic projection and display technology including apparatus and methods to provide three dimensional displays of live and/or static images which may be simultaneously viewed by one or more observers.
The display of projected images, whether static or moving, and whether based on, for example, conventional two-dimensional imaging or two-dimensional stereograms, typically relies on the use of relatively simple display screens that diffusively reflect the projected light. Such devices (e.g., overhead projector and movie screens) provide little in the way of reflected or displayed image flexibility, because they are usually planar in geometry, and possess no significant variation in their diffusive display capabilities across the surface of the device. Such limitations are undesirable to those seeking to display projected information in exciting or interesting ways, and particularly to those seeking to display stereographic images. On the other hand, some very specialized display devices, such as concave mirrors, possesses highly selective display capabilities. For example, light projected at a concave mirror is generally focused to a single focal point, thereby limiting the viewability of projected image. Of course, concave mirror are example of the opposite extreme in display technology because they are so dependent upon viwing position for displaying a projected image. Moreover, the techniques discussed so far, are not particularly suited for displaying projected stereographic images.
In addition to the conventional diffusive materials used to display projected images, holographic optical elements have been used in very specific ways to aid the display of projected images, or at the very least projected light. Holographic optical elements are specialized holograms specifically designed to diffract light in a particular way. The primary purpose of a holographic optical element is to serve some general optical function, as opposed to providing a viewer with an apparently three dimensional image, as is typically the case with traditional holograms. For example, holographic optical elements can be designed to operate as lenses, diffusers, mirrors (concave, convex, or planar), or a variety of other optical elements. Holographic optical elements can also perform well as diffuse reflectors. For example, U.S. Pat. No. 5,663,816 describes the use of very small reflective holographic elements in liquid crystal displays (LCDs) for the purpose of illuminating the display using ambient light and/or backlighting.
Unfortunately, the use of holographic optical elements as reflective devices, has traditionally been limited to relatively small applications, for example in LCDs, because of the difficulties associated with manufacturing larger holographic optical elements.
Accordingly, it is desirable to have large scale, highly selective display devices for projected images, including projected conventional two-dimensional images, two-dimensional stereograms, and holographic stereograms.
It has been discovered that large format, highly selective display screens can be formed from a plurality of holographic optical elements. In accordance with the teachings of the present invention, systems and methods are described to provide a holographic screen for display of static and/or dynamic projected conventional two-dimensional images, two-dimensional stereograms, and holographic stereograms. One aspect of the present invention includes presenting live-image three-dimensional displays using an array of two-dimensional data projectors, Another aspect includes projecting and enlarging static or dynamic source three-dimensional images (real objects, holograms, or other autostereoscopic images).
Large-scale projection screens can be provided which are capable of displaying and synthesizing images from multiple live-image two-dimensional projectors to form a live-image autostereoscopic three-dimensional display which can be viewed simultaneously by multiple observers.
One aspect of the present invention includes production of holographic optical elements (HOEs) which can behave like conventional lenses, mirrors, and diffusers that are also unlimited in size. Even analogs of complex combinations of conventional lenses, mirrors and diffusers can be produced. Conventional custom-designed lenses, mirrors, and diffusers, or their combinations, can otherwise be cumbersome and expensive to produce, especially in large scale. An automated production system allows large-scale custom HOEs to be produced much more efficiently and inexpensively.
Accordingly, one aspect of the present invention provides a system for projecting an image comprising a screen formed from at least one holographic optical element, and at least one projector for directing an image onto the screen, the screen presenting at least one viewzone through which an observer can view the image.
Another aspect of the present invention provides a system for producing and observing at least one autostereoscopic image. The system includes a screen formed from a plurality of holographic optical elements, and at least two projectors for directing an autostereoscopic image onto the screen. The screen has at least two viewzones through which at least one observer may view the autostereoscopic image.
Still another aspect of the present invention provides a system for producing and observing at least one autostereoscopic holographic display. The system includes a screen formed from a plurality of holographic optical elements and a three-dimensional image source with light coming therefrom and impinging upon the screen. The holographic optical elements cooperate with each other to produce the at least one autostereoscopic holographic display using the impinging light. The screen has at least two viewzones through which at least one observer may view the autostereoscopic holographic display.
Still another aspect of the present invention provides a system for producing and observing an image. The system includes a screen formed from a plurality of holographic optical elements. The screen is operable to reconstruct at least one point from a single point source.